This invention relates to a dockship, provided with an open hold extending from the forepeak bulkhead to a sterngate, arranged for the transport of heavy cargo loads such as reactor vessels which are to be loaded and unloaded by a gantry crane running on double boards forming structural strength members, or lighters which, when the sterngate is opened and the ship is submerged, can float in and out, and at least the upper portion of each of the double boards forming a buoyancy chamber, and said hold being provided with hatch covers.
The double boards, in which the buoyancy chambers are formed, have previously been constructed relatively wide in order to give the ship, particularly when loading and unloading heavy objects, sufficient stability, but the disadvantage thereof is that this is at the cost of the paying hold area.